import { reduce } from './reduce'; import { MonoTypeOperatorFunction } from '../types'; /** * The Min operator operates on an Observable that emits numbers (or items that can be compared with a provided function), * and when source Observable completes it emits a single item: the item with the smallest value. * * ![](min.png) * * ## Examples * Get the minimal value of a series of numbers * ```ts * import { of } from 'rxjs'; * import { min } from 'rxjs/operators'; * * of(5, 4, 7, 2, 8).pipe( * min(), * ) * .subscribe(x => console.log(x)); // -> 2 * ``` * * Use a comparer function to get the minimal item * ```typescript * import { of } from 'rxjs'; * import { min } from 'rxjs/operators'; * * interface Person { * age: number, * name: string * } * of( * {age: 7, name: 'Foo'}, * {age: 5, name: 'Bar'}, * {age: 9, name: 'Beer'}, * ).pipe( * min( (a: Person, b: Person) => a.age < b.age ? -1 : 1), * ) * .subscribe((x: Person) => console.log(x.name)); // -> 'Bar' * ``` * @see {@link max} * * @param {Function} [comparer] - Optional comparer function that it will use instead of its default to compare the * value of two items. * @return {Observable} An Observable that emits item with the smallest value. * @method min * @owner Observable */ export function min(comparer?: (x: T, y: T) => number): MonoTypeOperatorFunction { const min: (x: T, y: T) => T = (typeof comparer === 'function') ? (x, y) => comparer(x, y) < 0 ? x : y : (x, y) => x < y ? x : y; return reduce(min); }